It is desirable for a solid-state image pickup device to receive light from a subject into a photoreception section without reflection so as to be converted into an electrical signal by a photoelectric conversion function, thereby enhancing the conversion efficiency in the photoreception section.
For this purpose, it is desired to reduce, as far as possible, the reflection component of light that is caused on each of the interfaces of a laminated structure constituting a solid-state image pickup device. Further, reducing the reflection of light on each interface results in the reduction of such phenomena caused in the solid-state image pickup device as flare, ghost, blooming, and the like.
Therefore, technologies have been proposed in which, in a solid-state image pickup device arranged with a photoelectric conversion section configured to convert received light into electrical charges and a semiconductor substrate including the photoelectric conversion section, a multitude of regions having refractive indexes different from that of the semiconductor substrate are arranged between the surface of the side into which light enters and the photoelectric conversion section in the semiconductor substrate, thereby reducing the reflection of incident light (refer to PTL 1, for example).
The multitude of the regions having different refractive indexes formed on the semiconductor substrate are formed such that the area of the regions gets larger as the regions get nearer in depth to the surface of the side into which light enters in the semiconductor substrate and smaller as the regions get more remote in depth from this surface.
A moth-eye structure in which the semiconductor substrate is formed in a projecting (projected) conical manner from the light incident direction to the semiconductor substrate as described above can mitigate the drastic variation in the refractive index in the interface, one of the causes of light reflection, thereby reducing the influence of reflected light. That is, providing a moth-eye structure allows the refractive index to slowly vary along the incident direction of light, thereby reducing the reflection of light.